Advertisers need to track and target advertisements for users according to their interests across a proliferation of electronic devices, including mobile devices. Moreover, there is value to be had in finding and tracking groups of objects that share a common IP address, such as cookies, email hashes, device IDs and other forms of identity tokens that belong to a coherent group. However, merely tracking the IP address may have limited value, as routers can be reset or a mobile IP address may be updated due to changes in routing or location. A given IP address may be assigned to completely different groups of users over time, with each of the succeeding groups in time having unrelated different interests. Therefore, a way to identify and track groups or clusters of objects across changes in IP addresses over time would be desirable.